The present embodiments relate to a device for improving the filter effect of a filter.
Line filters are electronic components for reducing emitted interference caused by, among other things, ground leakage currents.
Ground leakage currents are undesired currents that flow to ground from a fault-free power circuit (e.g., via a ground capacitor) represented, for example, by a conductive part such as a grounded heat sink or a cable shielded with ground potential. Ground leakage currents may, for example, be caused by power electronics energy transformers that, as a result of switching operations, inject high-frequency switching transients into the power circuit. The ground circuit may close because another electrical component in the power circuit absorbs the ground leakage current again and feeds the ground leakage current back to the source of interference in the power circuit.
Ground leakage currents may be so energy-rich that the ground leakage currents interfere with or even damage the working of the electrical component absorbing the ground leakage current. In addition, the electrical lines between this electrical component and the source of interference act like an antenna and emit interference as a result of the ground leakage currents. This interferes with the functioning of other electrical components in the vicinity of the ground circuit. Excessively high ground leakage currents represent a danger for people, as the ground leakage currents may also discharge via the human body if conductive components are touched. Hence, an excessively large expansion of the ground circuit is to be prevented.
This is conventionally effected via the line filters, which short-circuit the input of the source of interference using interference-suppression capacitors for ground leakage currents in the ground and thus do not allow the ground circuit to extend to other electrical components in the power circuit. Because of the limited effect of the interference-suppression capacitors, chokes are also provided in order to damp the ground leakage currents that may not be fed back via the interference-suppression capacitors at the input of the source of interference. Since these ground leakage currents that may not be grounded may still be very energy-rich, the chokes have high inductance values that make the chokes expensive and take up a lot of space in a device for increasing electromagnetic compatibility.